Device for producing in a continuous manner reinforced profile belts from extruded material

ABSTRACT

A method of and device for producing reinforced profile belts, especially transmission belts, of extrudable material in a continuous manner successive portions of an endless belt are passed over a peripheral but different section of constant magnitude of a rotating wheel, preferably a wheel with peripheral teeth, so as together with said wheel to form a closed arc-shaped mold chamber. This mold chamber is sealed toward the outside while reinforcing strength members and extruded material from which the respective belt is to be made are continuously fed into the mold chamber.

This application is a division of Ser. No. 253,453, filed May 15, 1972,now U.S. Pat. No. 3,880,558.

The present invention relates to a method of and device for producing ina continuous manner reinforced profile belts of elastomeric material orsynthetic material, for instance, polyurethane or polyamide, or similarextruding material, with a pull-resistant insert extending in thelongitudinal direction of the belt. Such inserts may consist, forinstance, of a plurality of individual wires or threads. The presentinvention specifically relates to a method of and device for producingreinforced belts of the just mentioned type in a mold composed of twoparts the effective portions of which move along an endless path. Theseeffective portions, when brought together over a section of this path,form a closed mold while at the start of the section where the effectiveportions come together to form the closed mold there is provided in asealing manner the nozzle tube of an extruder through which the materialintended to form the respective belt is extruded into the mold. Thelength and the advancing speed of the parts forming the mold proper andthe extrusion speed of the extruder are so selected that the moldchambers located at that end of the closed mold which is opposite to theend of the closed mold into which the nozzle tube leads will be closedby solidified material and that in these mold chambers a post-pressureis produced to compensate for the shrinkage until the material hassolidified.

Reinforced profile belts in the form of toothed belts have heretoforebeen produced, for instance, by preparing a strand of synthetic materialbetween rollers while simultaneously at one side of the strand the teethare pressed-in whereas on the other side of the strand pull-resistantinserts are rolled into the strand. With this method, the extrudedmaterial has already cooled and solidified to such an extent that itmerely has the plasticity necessary for its deformability. This method,therefore, has the drawback that the pull-resistant inserts do not unitewith the material of the belt in such an intimate manner that thepulling forces can be conveyed by the teeth onto the insert without theinsert moving within the toothed belt. A further important drawbackconsists in that the material is able under the pressure exerted uponthe strand during the deformation of the material to escape to differentsides so that the deformed material will when it is cooling off shrinkin a non-controllable manner with the result that no precise and trueshape can be assured.

It is known to manufacture in a continuous manner profile strands fromordinary synthetic material in such a way that the two sections of adivided mold consist each of a plurality of individual form segmentswhich are linked to each other and form an endless chain while the twochains are so guided along a circular path that a section is formed atthe start of which the mold segments are moved together and in a sealingmanner slide over the nozzle tube of an extruder, while the segments atthe end of this section are lifted off again and while the hollowchamber of the mold of this section at the start of which plasticizedmaterial is injected is closed at its end by the solidified material.With profile strands of synthetic material produced by means of thisknown device, no reinforced profiles are involved which havepull-resistant inserts embedded in the material and extending in thelongitudinal direction of the profile. Moreover, this known device hasthe important drawback that with link chains tolerances are encounteredin the joints which add up and particularly in case of the manufactureof toothed belts which must have a very precise tooth pitch, result in anon-tolerable lack of precision.

For producing long conveyor belts of rubber, a continuous vulcanizingmethod has become known according to which an endless steel belt underpressure is looped around a portion of the circumference of a heated androtating vulcanizing drum while prefabricated pieces composed ofindividual plates are placed upon the steel belt which plates are pulledin between the steel belt and the vulcanizing drum and while passingtherebetween are vulcanized to form a continuous conveyor belt.

It is an object of the present invention to provide a method and deviceof the above described general character for producing reinforcedprofile belts of synthetic material, for instance, of polyurethane ofpolyamide, or similar extrudable material, which will solve the problemof an economical continuous manufacture of reinforced profile belts aswell as the simultaneous generation of an injection pressure necessaryfor a complete molding and for maintaining true dimensions of theproduct.

It is a further object of this invention to provide a method of anddevice for making reinforced profile belts as set forth in the precedingparagraph which will also assure the necessary post-pressure in the moldchambers as it is required for compensating for shrinkage whilesimultaneously the reinforcing inserts are properly embedded in theextruded plasticized but still liquid material and a high precision ofthe produced product will be assured as it is necessary in particularfor the pitch of the toothed belts.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawings, in which:

FIG. 1 represents a diagrammatic illustration of a device according tothe invention, partly sectioned along the line I--I of FIG. 2.

FIG. 2 illustrates a section of a portion of the device of FIG. 1, saidsection being taken along the line II--II of FIG. 1.

FIG. 3 is a cutout from FIG. 1 on an enlarged scale.

FIGS. 4 and 5 illustrate, similar to FIGS. 1 and 2, a modified deviceaccording to the invention.

FIGS. 6 and 7 shown further modifications of the device in anillustration similar to that of FIG. 3.

Starting from the manufacturing method of the type set forth in theintroductory portion of the specification, the problem underlying thepresent invention has been solved by partially looping an endless beltover a portion of a rotating wheel whereby a closed arc-shaped mold withmold chambers between the belt and the wheel is formed while at thestart of this closed mold the material is injected into the moldchambers and a pull-resistant insert is between the still open moldsection ahead of the nozzle tube mouth fed to the hollow mold chambersof the closed mold section behind the nozzle mouth. This is carried outin such a sealing manner that along the insert no connection existsbetween the closed mold section behind the nozzle tube mouth and theopen mold section ahead of the nozzle tube mouth. For producing a beltwith teeth on one side only, the mold wheel is, for instance, in anadvantageous manner at its circumference provided with hollow chamberscorresponding to the shape of the teeth to be formed. These hollowchambers are arranged at a precise gear-like pitch and in order toobtain a closed mold section may be covered up by a simple flat steelband in such a way that a toothed belt can be produced in a continuousmanner with very high precision and true tooth pitch. The nozzle tubemouth seals the hollow chambers of the mold at the start of the closedmold section, and the looping angle of the molding gear may inconformity with the advancing speed of the closed mold section and inconformity with the extrusion speed of the extruder be so dimensionedthat the material will have solidified and the hollow chambers of themold at the end of the closed mold section will be closed by thesolidified material before the steel band is lifted off again from themolding gear. Consequently, the material can be injected at thenecessary high injection pressure, and the necessary post-pressure forcompensating for shrinkage can be maintained until the material hassolidified in the closed hollow chambers of the mold. Simultaneouslywith the extrusion of the plasticized or liquid material into the closedmold section, pull-resistant inserts are introduced into the closed moldsection so that these pull-resistant inserts will directly behind thenozzle tube mouth be surrounded by the extruded material and in this waywill be intimately united with the material or the profile belt.Inasmuch as the pull-resistant insert is in a sealing manner fed intothe closed mold section, the injection pressure cannot unduly drop atthat area where the insert is being fed to the mold. The feeding of theinsert into the closed mold section in a sealing manner may be effected,if the insert consists of a plurality of individual wires,advantageously by pulling each wire through a seal-equipped passage inthe nozzle mouth piece.

If a belt is to be produced which has teeth on both sides, also theendless band may be provided with hollow mold chambers. In such aninstance the band may be simple means be brought into mesh with themolding gear so that a slip of the band on the molding gear will beavoided and a precise location of the teeth of one side of the toothedbelt relative to the teeth on the other side of the toothed belt will beassured.

Referring now to the drawings in detail, FIGS. 1 to 3 illustrate adevice for producing in a continuous manner a reinforced toothed beltwith teeth on one side of the belt and with pull-resistant wire insertsextending in the longitudinal direction of the belt. The divided moldcomprises a rotating mold gear 1 and an endless flat steel band 2. Thesteel band 2 is by means of an upper guiding roller 3 moved toward themolding gear 1 and after a certain looping stroke is by means of a lowerguiding roller 4 lifted off again from the molding gear 1 and by meansof a deviating roller 5 is in a cycle returned to the guiding roller 3.

The molding gear 1 comprises a central profile drum 6 and two lateraldiscs 7 which are preferably detachably connected to the drum 6, forinstance, by screws. The drum 6 has its circumference provided withteeth 8 and tooth spaces 9, while the tooth spaces 9 represent thehollow chambers of the mold which are to be filled with extrudedmaterial and eventually will form the teeth of the belt to be produced.The hollow chambers are covered by the steel band 2 moved toward themolding gear 1 and are closed thereby while the section of the steelband 2 between the two guiding rollers 3 and 4 and that portion of themolding gear 1 around which the respective band section is looped formsthe closed mold section. In order to assure that the steel band willmaintain a desired distance from the crest of the teeth 8 in conformitywith the desired thickness of the belt to be produced, the two lateraldiscs 7 are provided with a shoulder 10 on which the steel band 2 rests.The lateral outer edges of the shoulders 10 of discs 7 are provided withguiding edges 11 which precisely guide the steel band 2 on the moldinggear 1 in a direction transverse to the direction of movement of theband. By exchanging the drum 6, the device according to the presentinvention may in a simple manner be used for the production of profilebelts having different thickness and different types of teeth.

The closed mold section formed by the steel band 2 and the molding gear1 is tightly closed at its start by a nozzle mouth piece 13 connected tothe nozzle tube 12. As more clearly shown in FIG. 3, the upper portionof the nozzle mouth piece 13 sealingly engages a circular arc-shapedsealing surface of the steel band 2 looped around the guiding roller 3.The lower portion of the nozzle mouth piece 13 sealingly engages acircular arc-shaped sealing surface at the crest surface 14 of aplurality of teeth 8 of drum 6. The inner surfaces of the two lateraldiscs 7 sealingly slide on the nozzle mouth piece 13. The nozzle mouthpiece 13 is provided with a bore 15 through which the plasticizedmaterial is injected into the closed mold section. Furthermore, thenozzle mouth piece 13 is provided with a plurality of passages 16through which one reinforcing wire 17 each is introduced from theoutside into the closed mold section. These passages 16 are equippedwith seals 18 sealingly surrounding the wires 17.

The nozzle mouth piece 13, the molding gear 1, and the upper guidingroller 3 may advantageously be equipped with non-illustrated heating orcooling means. By exchanging the nozzle mouth piece 13 at the nozzletube 12, the device can be changed over for the employment ofreinforcing inserts of different thickness and of a different number ofreinforcing inserts. Furthermore, by the use of differently wide nozzlemouth pieces, a differently wide drum and a steel band of a differentwidth, the device according to the invention can in a simple manner bechanged over for the production of profile belts of different widths.

As will be evident from FIG. 6, the teeth 8 of the drum 6 may beequipped with winding noses 19 on which the reinforcing inserts 17 willrest after leaving the nozzle mouth piece 13. These noses 19 will keepthe reinforcing inserts 17 spaced from the crest surfaces 14 of theteeth 8 so that the reinforcing inserts 17 will be embedded in thematerial in the central range of the belt thickness. When employing suchnoses 19, however, the finished product will have the reinforcinginserts at the contact points with the noses not covered with syntheticmaterial or the like, but the inserts will be exposed at these areas.Such exposed areas of the reinforcing inserts will be avoided bydesigning the nozzle mouth piece 13 as shown in FIG. 3. With thisdesign, the bore 15 will have a main exit 20 leading into the closedmold section for the plasticized material and simultaneously for thereinforcing insert 17 which brings about an intimate covering of thereinforcing inserts with plasticized material. In the direction ofrotation of the molding gear 1 and ahead of the main exit 20, thesliding and sealing surface of the nozzle mouth piece 13, which surfacecooperates with the circumference of the molding gear, is provided withan additional nozzle bore 21. By means of this additional nozzle bore21, prior to each tooth entering the range of the closed mold section, athin layer of synthetic material is deposited upon the crest surface 14of each tooth 8. This deposited layer firmly unites with the materialextruded through the main exit 20. It should be noted, however, thatthis deposited material, if desired aided by a corresponding temperaturecontrol of the molding gear, is solidified to such an extent that itwill keep the insert 17 properly spaced from the crest surfaces 14 ofthe teeth. In this way, on one hand, winding noses become superfluousand, on the other hand, it will be assured that the pull-resistantinsert will have no longer any exposed areas where corrosion mightoccur, but will be fully covered by a protective layer of the materialfrom which the belt is made.

FIGS. 4 and 5 shown an embodiment of the device for making a toothedbelt with profiles on both sides. In this instance, the steel band 22 isbetween its two margins which sealingly rest against the discs 7 of themolding gear 1 provided with bulges 23 which are pressed out toward thatside which faces away from the molding gear. These bulges form hollowchambers and will create profiles on the back side of the toothed belt.

Finally, FIG. 7 illustrates a design of a steel band 24 for producingtoothed belts with teeth on both sides. The steel band 24 hasperforations 25 arranged at a certain pitch which are on that side,which faces away from the molding gear, covered by hoods 26. These hoods26 form on the band 24 hollow chambers which are adapted to be filledwith plasticized material through the perforations 25 and which bringabout the tooth shape on the back side of the profile belt. The lateraldisc of the molding gear may be equipped with cams 27 or the like whichin a tooth-like manner mesh with corresponding recesses 28 in the hoods26 in order in this way to prevent a slip between the steel band 24 andthe molding gear 1. This interengagement may be such that within therange of the closed mold section the hollow mold chambers formed by thehoods 26 in the region of the closed mold section will be locatedopposite to the hollow mold chambers formed by the tooth spaces 9 of themolding gear 1 or will be located in an offset manner relative to thelatter if this should be desired.

It is, of course, to be understood that the present invention is, by nomeans, limited to the specific embodiments illustrated in the drawingsbut also comprises any modifications within the scope of the appendedclaims. It is further to be understood that the term reinforced profilebelts as used in the present specification and claims also includestransmission belts, V-belts, toothed belts, conveyor belts and the like,which have pull-resistant inserts, for instance, in the form of threads,wires, strands, cables, or bands, of synthetic material or metal.

We claim:
 1. An apparatus for producing in a continuous processreinforced belts of pressure injectable material with pull-resistantreinforcement insert members extending longitudinally therein,comprising: a rotatable wheel and an endless band looped over andengaging a peripheral portion of said forming wheel with a continuouschannel between said band and forming wheel closed on both sides so thatin response to rotation of said forming wheel and movement of said banda closed curved mold is formed therebetween, closed injection nozzlemeans positioned between forming wheel and said band at the entrance tosaid mold, said injection nozzle means having an inlet to receivemoldable material under pressure and a passage leading to a dischargeoutlet between said forming wheel and band opening into the entrance tosaid mold, said passage means and discharge outlet also receivingcontinuous reinforcement inserts with sealing means in apertures throughwhich said inserts pass into the mold, said nozzle means also being insealing engagement with said forming wheel and band to prevent escape ofmoldable material under pressure from said nozzle, so that said moldablematerial is injected under pressure into said mold and surrounding saidinserts, and the material in said mold is maintained under pressureuntil said material is solidified, said forming wheel being formed withpockets in its periphery opening toward said band and separated bytransverse radial walls to form chambers for molding teeth on said belt,said transverse walls having ribs on their outer edges substantiallynarrower than the thickness of said walls to support the reinforcinginserts on substantially line contact.
 2. A device for producing in acontinuous process reinforced profile belts of a pressure injectablematerial with a pull-resistant reinforcement insert extendinglongitudinally therein, which includes: a rotatable forming wheel and anendless band looped over and engaging on at least a peripheral portionof said rotatable forming wheel so that in response to a rotation ofsaid forming wheel together with said band successive portions of saidband sealingly pass around said forming wheel and form a closed curvedmold therewith, injection nozzle means located between said formingwheel and said band at the start of said mold, said injection nozzlemeans sealingly engaging said band and said forming wheel for tightlyclosing said mold at its start and having passage means for conveyinginjectable material under pressure into said mold, said injection nozzlemeans also including passage means for sealingly introducingreinforcement inserts therethrough into said mold, said forming wheelbeing formed with pockets in its periphery, opening toward said band andseparated by transverse radial walls to form chambers for molding teethon said belt, said transverse walls having ribs on their outer edgessubstantially narrower than the thickness of said walls to support thereinforcing inserts on substantially line contact.